Sensor-driven lighting units monitor a characteristic of the environment with a sensor and utilize the sensor data to control the light source of the lighting unit, or to reveal other information about the environment. The most common example of sensor-driven lighting units are systems that monitor light levels using integrated photocells that measure ambient light level. For example, night lights use ambient light to turn on when ambient light levels decrease and to turn off when ambient light levels increase. As another example, some sensor-driven luminaries measure reflected light coming from a surface below and dim the light output when the light level exceeds a predefined light level. Since these luminaires integrate all the reflected light into a single light level, there can be incorrect measurements such as in the case of striped patterns casted by blinds or shadows casted by trees. Accordingly, these solutions often provide sub-optimal light level monitoring, thereby resulting in an overall poor system performance. Further, these systems are unable to determine or extract depth queue information about objects within the lighting environment.
Another common example of sensor-driven lighting units are systems that monitor the occupancy state of a room. These luminaires use a variety of mechanisms, including ambient light levels, motion detection, and thermal imaging to detect a presence in a room and control the luminaire accordingly. For example, in an office setting, objects with a thermal signature such as people are detected by a thermal imager and thus informs the lighting system that a person is present. These thermal imaging luminaires function largely to detect the presence of an individual in a room. However, there is other information that can be extracted from the thermal imaging to maximize the efficiency and functionality of the lighting system.
Accordingly, there is a continued need in the art for methods and lighting systems that utilize a lighting unit with a thermal imager to extract information about a lighting environment, and more specifically to acquire one or more depth queues from extracted thermal shadows within the lighting environment.